> 2022年6月6日 16:45，mingzhe.zou@xxxxxxxxxxxx 写道：
>
> From: mingzhe <mingzhe.zou@xxxxxxxxxxxx>
>
>
[snipped]
> We want to use those invalid_uuid slots carefully. Because, the bkey of the inode
> may still exist in the btree. So, we need to check the btree before reuse it.
>
> Signed-off-by: mingzhe <mingzhe.zou@xxxxxxxxxxxx>
> ---
> drivers/md/bcache/btree.c | 35 +++++++++++++++++++++++++++++++++++
> drivers/md/bcache/btree.h | 1 +
> drivers/md/bcache/super.c | 15 ++++++++++++++-
> 3 files changed, 50 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
> index e136d6edc1ed..a5d54af73111 100644
> --- a/drivers/md/bcache/btree.c
> +++ b/drivers/md/bcache/btree.c
> @@ -2755,6 +2755,41 @@ struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *c,
> return ret;
> }
>
> +static bool check_pred(struct keybuf *buf, struct bkey *k)
> +{
> + return true;
> +}
> +
> +bool bch_btree_can_inode_reuse(struct cache_set *c, size_t inode)
> +{
> + bool ret = true;
> + struct keybuf_key *k;
> + struct bkey end_key = KEY(inode, MAX_KEY_OFFSET, 0);
> + struct keybuf *keys = kzalloc(sizeof(struct keybuf), GFP_KERNEL);
> +
> + if (!keys) {
> + ret = false;
> + goto out;
> + }
> +
> + bch_keybuf_init(keys);
> + keys->last_scanned = KEY(inode, 0, 0);
> +
> + while (ret) {
> + k = bch_keybuf_next_rescan(c, keys, &end_key, check_pred);
> + if (!k)
This is a single thread iteration, for a large filled cache device it can be very slow. I observed 40+ minutes during my testing.
Coly Li
> + break;
> +
> + if (KEY_INODE(&k->key) == inode)
> + ret = false;
> + bch_keybuf_del(keys, k);
> + }
> +
> + kfree(keys);
> +out:
> + return ret;
> +}
> +
> void bch_keybuf_init(struct keybuf *buf)
> {
> buf->last_scanned = MAX_KEY;
> diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h
> index 1b5fdbc0d83e..c3e6094adb62 100644
> --- a/drivers/md/bcache/btree.h
> +++ b/drivers/md/bcache/btree.h
> @@ -413,4 +413,5 @@ struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *c,
> struct bkey *end,
> keybuf_pred_fn *pred);
> void bch_update_bucket_in_use(struct cache_set *c, struct gc_stat *stats);
> +bool bch_btree_can_inode_reuse(struct cache_set *c, size_t inode);
> #endif
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index 3563d15dbaf2..31f7aa347561 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -544,11 +544,24 @@ static struct uuid_entry *uuid_find(struct cache_set *c, const char *uuid)
> return NULL;
> }
>
> +static struct uuid_entry *uuid_find_reuse(struct cache_set *c)
> +{
> + struct uuid_entry *u;
> +
> + for (u = c->uuids; u < c->uuids + c->nr_uuids; u++)
> + if (!memcmp(u->uuid, invalid_uuid, 16) &&
> + bch_btree_can_inode_reuse(c, u - c->uuids))
> + return u;
> +
> + return NULL;
> +}
> +
> static struct uuid_entry *uuid_find_empty(struct cache_set *c)
> {
> static const char zero_uuid[16] = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
> + struct uuid_entry *u = uuid_find(c, zero_uuid);
>
> - return uuid_find(c, zero_uuid);
> + return u ? u : uuid_find_reuse(c);
> }
>
> /*
> --
> 2.17.1
>
